Hybrid Heating System

ABSTRACT

Hybrid heating system including: a heat pump water heating system; sensors, for measuring a system parameter; an input arrangement providing cost data pertaining to a first power cost for supplying power to the heat pump system, and to cost information pertaining to a second power cost for operating a conventional heating system; a processor storing criteria specifying when to operate the heat pump and conventional systems, the processor receiving and processing: cost data; cost information; system parameter data; flow information on a heat exchange system circulation arrangement, and heat pump system power consumption information; and concurrently operating, upon demand, the heat pump system and a chiller system in opposite heating modes; wherein, when the chiller system operates in a cooling mode, the processor processes the cost data and information, system parameter data, and flow and power consumption information, and controls the systems based on the criteria.

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 13/105,921 filed on May 12, 2011, which is acontinuation-in-part of PCT/IL2009/001088, filed on Nov. 18, 2009, whichclaims priority from U.S. Provisional Patent Application Ser. No.61/115,561 filed on Nov. 18, 2008. U.S. Provisional Patent ApplicationSer. No. 61/115,561 is hereby incorporated by reference for all purposesas if fully set forth herein.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to hybrid heating systems.

Consumer demand for electricity is generally not uniform over the courseof a 24-hour period. Electric companies thus find that during peak hoursthe demand for electricity approaches, or may even exceed, theelectricity generating capacity of the company. On the other hand,during hours when the demand for electricity is very low, for example,during part of the night, a significant portion of the electricitygenerating capacity is not utilized. Electric companies thus search forschemes to induce consumers to transfer some of their electricityconsumption from the peak hours of demand to the off-peak hours. Forexample, many electric companies have instituted a pricing schemewherein the cost of electricity to the consumer is highest during theperiod of peak demand and is significantly lower during the hours of lowdemand. Such a pricing scheme is sometimes known as a “time-of-use”pricing scheme.

Systems that generate hot water and/or steam for bathing, ambientheating and other uses may use electricity or fossil fuels as the energysource. In contrast to heating by electricity, the cost of water heatingby fossil fuel burning may remain substantially constant over any24-hour period. Therefore, in a time-ofuse pricing scheme forelectricity use, water heating by electricity during peak hours may bemore expensive than heating by burning a fossil fuel. On the other hand,water heating by electricity during off-peak hours may be cheaper thanheating by burning fossil fuels.

The present inventors have recognized a need for improved hybrid heatingsystems, and methods of operating such systems.

SUMMARY OF THE INVENTION

According to the teachings of the present invention there is provided ahybrid heating system including: (a) a heat pump water heating systemincluding: (i) a pressurizing arrangement, associated with a refrigerantcirculation pipe, adapted to increase a pressure of a first refrigerantfluid to produce a pressurized refrigerant fluid; (ii) a first heatexchange system including: a primary circulation arrangement, including,and fluidly communicating with, a first heat exchanger, the firstexchanger fluidly communicating with the refrigerant circulation pipe,the first exchanger and the primary circulation arrangement adapted toeffect an indirect heat exchange between a first flow of liquid and thepressurized refrigerant fluid, whereby heat is transferred from thepressurized refrigerant fluid to the first flow of liquid to produce afirst heated flow of liquid, and whereby an enthalpy-reduced refrigerantfluid is produced, the heat exchange system optionally including atleast a secondary circulation arrangement having, and fluidlycommunicating with, a secondary heat exchanger, (iii) a depressurizingarrangement, fluidly communicating with the refrigerant circulationpipe, and adapted to receive the enthalpy-reduced refrigerant fluid andto reduce a pressure thereof, to produce a depressurized refrigerantfluid having a lower pressure than the enthalpy-reduced fluid, and (iv)a second heat exchanger, the second exchanger fluidly communicating withthe circulation pipe, and adapted to effect an exchange of heat betweenthe depressurized refrigerant fluid and a heat source, whereby the firstrefrigerant fluid is produced; (b) a conventional heating systemincluding at least one conventional heater having a surface heatexchanger, and a second primary circulation arrangement fluidlycommunicating with the surface exchanger, the second primary circulationarrangement adapted to effect an exchange of heat between the surfaceheat exchanger and a second flow of liquid to produce a second heatedflow of liquid; (c) a plurality of sensors, each adapted to measure atleast one system parameter, the plurality of sensors including at leasta first temperature sensor and a second temperature sensor associatedwith the heat exchange system; (d) an input arrangement adapted toprovide cost data pertaining to a first power cost for supplying powerto the heat pump water heating system, and to cost informationpertaining to a second power cost for operating the conventional heatingsystem, and (e) a processor including a memory storing criteriaspecifying when to operate the heat pump water heating system, and whento operate the conventional heating system, the processor adapted toreceive and to process: (i) the cost data; (ii) the cost information;(iii) system data pertaining to the system parameters; (iv) flowinformation pertaining to a flowrate of a liquid within any thecirculation arrangement of the first heat exchange system, and (v) powerconsumption information pertaining to a power consumption of at least aportion of the heat pump water heating system, the processor furtheradapted to calculate and compare a cost of operating the heat pump waterheating system and the conventional heating system, based on the costdata, the cost information, the system data, the flow information, andthe consumption information, and based on the criteria, to controloperation of the heating systems.

According to another aspect of the present invention there is provided ahybrid heating system including: (a) a heat pump water heating systemincluding: (i) a pressurizing arrangement, associated with a refrigerantcirculation pipe, adapted to increase a pressure of a first refrigerantfluid to produce a pressurized refrigerant fluid; (ii) a first heatexchange system including: a primary circulation arrangement, including,and fluidly communicating with, a first heat exchanger, the firstexchanger fluidly communicating with the refrigerant circulation pipe,the first exchanger and the primary circulation arrangement adapted toeffect an indirect heat exchange between a first flow of liquid and thepressurized refrigerant fluid, whereby heat is transferred from thepressurized refrigerant fluid to the first flow of liquid to produce afirst heated flow of liquid, and whereby an enthalpy-reduced refrigerantfluid is produced, the heat exchange system optionally including atleast a secondary circulation arrangement having, and fluidlycommunicating with, a secondary heat exchanger, (iii) a depressurizingarrangement, fluidly communicating with the refrigerant circulationpipe, and adapted to receive the enthalpy-reduced refrigerant fluid andto reduce a pressure thereof, to produce a depressurized refrigerantfluid having a lower pressure than the enthalpy-reduced fluid, and (iv)a second heat exchanger, the second exchanger fluidly communicating withthe circulation pipe, and adapted to effect an exchange of heat betweenthe depressurized refrigerant fluid and a heat source, whereby the firstrefrigerant fluid is produced; (b) a conventional heating systemincluding at least one conventional heater having a surface heatexchanger, and a second primary circulation arrangement fluidlycommunicating with the surface exchanger, the second primary circulationarrangement adapted to effect an exchange of heat between the surfaceheat exchanger and a second flow of liquid to produce a second heatedflow of liquid, the hybrid heating system configured to direct the firstand second heated flows of liquid towards an identical consumer; (c) aninput arrangement adapted to provide cost data pertaining to a firstpower cost for supplying power to the heat pump water heating system,and to cost information pertaining to a second power cost for operatingthe conventional heating system, and (d) a processor including a memorystoring criteria specifying when to operate the heat pump water heatingsystem, and when to operate the conventional heating system, theprocessor adapted to receive and to process: (i) the cost data; and (ii)the cost information, the processor further adapted to calculate andcompare a cost of operating the heat pump water heating system and theconventional heating system, based on the cost data and the costinformation, and based on the criteria, to control operation of theheating systems, the processor further adapted to control the operationof the heat pump water heating system to increase a thermal storage of athermal storage arrangement, associated with the hybrid heating system,responsive to a forecast pertaining to a hot water load or demand fromthe consumer or a consumer network.

According to yet another aspect of the present invention there isprovided a hybrid heating system including: (a) a heat pump waterheating system including: (i) a pressurizing arrangement, associatedwith a refrigerant circulation pipe, adapted to increase a pressure of afirst refrigerant fluid to produce a pressurized refrigerant fluid; (ii)a first heat exchange system including: a primary circulationarrangement, including, and fluidly communicating with, a first heatexchanger, the first exchanger fluidly communicating with therefrigerant circulation pipe, the first exchanger and the primarycirculation arrangement adapted to effect an indirect heat exchangebetween a first flow of liquid and the pressurized refrigerant fluid,whereby heat is transferred from the pressurized refrigerant fluid tothe first flow of liquid to produce a first heated flow of liquid, andwhereby an enthalpy-reduced refrigerant fluid is produced, the heatexchange system optionally including at least a secondary circulationarrangement having, and fluidly communicating with, a secondary heatexchanger, (iii) a depressurizing arrangement, fluidly communicatingwith the refrigerant circulation pipe, and adapted to receive theenthalpy-reduced refrigerant fluid and to reduce a pressure thereof, toproduce a depressurized refrigerant fluid having a lower pressure thanthe enthalpy-reduced fluid, and (iv) a second heat exchanger, the secondexchanger fluidly communicating with the circulation pipe, and adaptedto effect an exchange of heat between the depressurized refrigerantfluid and a heat source, whereby the first refrigerant fluid isproduced; (b) a conventional heating system including at least oneconventional heater having a surface heat exchanger, and a secondprimary circulation arrangement fluidly communicating with the surfaceexchanger, the second primary circulation arrangement adapted to effectan exchange of heat between the surface heat exchanger and a second flowof liquid to produce a second heated flow of liquid, the hybrid heatingsystem configured to direct the first and second heated flows of liquidtowards an identical consumer; (c) at least one sensor, including atleast one temperature sensor; (d) an input arrangement adapted toprovide cost data pertaining to a first power cost for supplying powerto the heat pump water heating system, and to cost informationpertaining to a second power cost for operating the conventional heatingsystem, and (e) a processor including a memory storing criteriaspecifying when to operate the heat pump water heating system, and whento operate the conventional heating system, the processor adapted toreceive and to process: (i) the cost data; and (ii) the costinformation; the processor adapted to control operation of theconventional heating system and the heat pump water heating system basedon the criteria, the processor further adapted to calculate and comparea cost of operating the heat pump water heating system and theconventional heating system, based on the cost data and the costinformation, and based on a first predicted efficiency of the heat pumpwater heating system, the predicted efficiency dependent on at least oneparameter selected from the group of parameters consisting of an ambientparameter, an inlet liquid temperature to the first exchanger, and aninlet liquid flowrate to the first exchanger, and based on the criteria,to control operation of the heating systems.

According to yet another aspect of the present invention there isprovided a hybrid heating system substantially as described herein, thesystem including any feature described, either individually or incombination with any feature, in any configuration.

According to yet another aspect of the present invention there isprovided a method of producing and supplying heated water to a consumeror to a consumer network, substantially as described herein, the methodincluding any feature described, either individually or in combinationwith any feature, in any configuration.

According to further features in the described preferred embodiments,the processor is adapted to receive and to process the power consumptioninformation pertaining to a total power consumption of the heat pumpwater heating system.

According to still further features in the described preferredembodiments, the hybrid system is configured to direct the first heatedflow of liquid and the second heated flow of liquid towards an identicalconsumer/consumer network.

According to still further features in the described preferredembodiments, the processor is adapted to control operation of theconventional heating system and the heat pump water heating system basedon the criteria, to reduce or minimize a cost.

According to still further features in the described preferredembodiments, the processor is adapted to calculate and compare a cost ofoperating the heat pump water heating system and the conventionalheating system, to control operation of the heating systems, to reduceor minimize a cost.

According to still further features in the described preferredembodiments, the processor is adapted to utilize the cost data and todecide whether to operate the conventional heating system or to operatethe heat pump water heating system.

According to still further features in the described preferredembodiments, the second heat exchanger is adapted whereby the exchangeof heat between the depressurized refrigerant fluid and the heat sourceis effected by means of a forced air circulation unit. The forced aircirculation unit may be adapted to direct a supply of ambient air, asthe heat source, to effect the exchange of heat.

According to still further features in the described preferredembodiments, the hybrid heating system further includes a powerconsumption sensor providing the power consumption information.

According to still further features in the described preferredembodiments, the hybrid heating system further includes a flow sensor,associated with any the circulation arrangement, and providing the flowinformation.

According to still further features in the described preferredembodiments, the first sensor is disposed in an upstream location withrespect to the first heat exchanger, and the second sensor disposed in adownstream location with respect to the first heat exchanger.

According to still further features in the described preferredembodiments, the processor is adapted to receive and to process flowinformation pertaining to a flowrate of the second flow of liquid.

According to still further features in the described preferredembodiments, the processor is adapted to calculate a heat transferred bythe heat pump system to a liquid within the first heat exchange system,based partly on a temperature differential between the secondtemperature sensor and the first temperature sensor.

According to still further features in the described preferredembodiments, the primary circulation arrangement of the first heatexchange system is adapted to direct the first heated flow of liquidtowards a consumer.

According to still further features in the described preferredembodiments, the secondary circulation arrangement of the first heatexchange system is adapted to direct a heated flow of liquid towards aconsumer.

According to still further features in the described preferredembodiments, the first power cost pertains to a cost of electricity.

According to still further features in the described preferredembodiments, the second power cost pertains to a cost of fuel foroperating the conventional heating system.

According to still further features in the described preferredembodiments, the pressurizing arrangement includes a compressionarrangement, the first refrigerant fluid is a first refrigerant gas, andthe pressurized refrigerant fluid is a compressed refrigerant gas.

According to still further features in the described preferredembodiments, the compression arrangement includes a compressor, adaptedto be electrically connected to a power supply and fluidly communicatingwith the refrigerant circulation pipe, the compressor adapted tocompress the first refrigerant gas to produce the compressed gas.

According to still further features in the described preferredembodiments, the heat pump water heating system is adapted to condenseat least a portion of the compressed refrigerant gas into theenthalpy-reduced refrigerant fluid to produce a refrigerant liquid.

According to still further features in the described preferredembodiments, the hybrid heating system further includes a thermalstorage arrangement adapted to fluidly communicate with the circulationarrangement, the processor further adapted to control the heat pumpwater heating system to increase a thermal storage of the thermalstorage arrangement responsive to a time-of-use pricing scheme.

According to still further features in the described preferredembodiments, the depressurizing arrangement includes an expansion valve,fluidly communicating with the circulation pipe and adapted to reduce apressure and a temperature of the enthalpy-reduced refrigerant fluid.

According to still further features in the described preferredembodiments, based on the criteria, the processor is adapted to operatethe conventional heating system and the heat pump water heating systemin a simultaneous mode.

According to still further features in the described preferredembodiments, the processor is further adapted to control operation ofthe conventional heating system and the heat pump water heating systembased on a first predicted efficiency of the heat pump water heatingsystem, the predicted efficiency dependent on at least one parameterselected from the group of parameters consisting of an ambientparameter, an inlet liquid temperature to the first exchanger, and aninlet liquid flowrate to the first exchanger.

According to still further features in the described preferredembodiments, the processor is further adapted to control operation ofthe conventional heating system and the heat pump water heating systembased on a second predicted efficiency of the conventional heatingsystem.

According to still further features in the described preferredembodiments, the second predicted efficiency is dependent on a forecastof a hot water load or demand.

According to still further features in the described preferredembodiments, the second predicted efficiency is dependent on a variableefficiency parameter of the conventional heating system.

According to still further features in the described preferredembodiments, the variable efficiency parameter provides an estimatedefficiency of the conventional heating system based on a time positionwithin a maintenance cycle of the conventional heating system.

According to still further features in the described preferredembodiments, the at least one ambient parameter includes an ambienttemperature.

According to still further features in the described preferredembodiments, the at least one ambient parameter includes an ambienthumidity.

According to still further features in the described preferredembodiments, the conventional heater has a thermal efficiency of lessthan 99%.

According to still further features in the described preferredembodiments, the conventional heater is selected from the group ofheaters consisting of fossil fuel burning heaters, biomass burningheaters, and electrical resistance heaters.

According to still further features in the described preferredembodiments, the conventional heater includes at least one steam boiler.

According to still further features in the described preferredembodiments, the hybrid heating system includes at least one solarheater.

According to still further features in the described preferredembodiments, the criteria are at least partly based on efficiencyinformation pertaining to the conventional heating system.

According to still further features in the described preferredembodiments, the criteria are at least partly based on coefficient ofperformance (COP) information pertaining to the heat pump water heatingsystem.

According to still further features in the described preferredembodiments, the COP information is derived from the data pertaining tothe system parameters, the flow information, and the power consumptioninformation.

According to still further features in the described preferredembodiments, the efficiency information includes a calculated efficiencybased on an actual efficiency of the conventional heating system over aparticular period of time.

According to still further features in the described preferredembodiments, the efficiency information includes a calculated efficiencyfurther based on a current time position within a maintenance time cycleof the conventional heating system.

According to still further features in the described preferredembodiments, the COP information includes an actual COP of the heat pumpwater heating system over at least one particular period of time.

According to still further features in the described preferredembodiments, the COP information includes an average COP of the heatpump water heating system, the average based on a plurality of the oneparticular period of time.

According to still further features in the described preferredembodiments, the COP information is based on a plurality of actual COPdata previously attained by the heat pump system.

According to still further features in the described preferredembodiments, the plurality of actual COP data is weighted according to asimilarity criterion between past operating conditions and presentoperating conditions of the heat pump water heating system.

According to still further features in the described preferredembodiments, the COP information is based on a regression of a pluralityof actual COP data previously attained by the heat pump system, whereina weighting of the actual COP data is based on a similarity criterionbetween past operating conditions and present operating conditions ofthe heat pump water heating system.

According to still further features in the described preferredembodiments, the past and present operating conditions include at leastone of an ambient temperature, a relative or absolute humidity, an inletliquid temperature to the first exchanger, an inlet liquid flowrate tothe first exchanger, and an energy demand.

According to still further features in the described preferredembodiments, the hybrid heating system further includes an airconditioning system adapted to cool at least one volume, space or room,the heat pump water heating system and the air conditioning systemadapted to operate, upon demand, concurrently in opposite heating modes,and wherein, when the air conditioning system operates in cooling mode,the processor is adapted to receive and to process the cost data, thecost information, data pertaining to the system parameters, flowinformation pertaining to a flowrate of the first flow of liquid, andpower consumption information pertaining to a power consumption of atleast a portion of the heat pump water heating system, and to controloperation of the conventional heating system and the heat pump waterheating system based on the criteria.

According to still further features in the described preferredembodiments, the air conditioning system is a heat pump conditioningsystem further adapted to heat the at least one volume, space, or room.

According to still further features in the described preferredembodiments, the heat pump water heating system and the air conditioningsystem adapted to operate, upon demand, concurrently in a heating mode,and wherein, when the air conditioning system operates in the heatingmode, the processor is adapted to receive and to process the cost data,the cost information, data pertaining to the system parameters, flowinformation pertaining to a flowrate of the first flow of liquid, andpower consumption information pertaining to a power consumption of atleast a portion of the heat pump water heating system, and to controloperation of the conventional heating system and the heat pump waterheating system based on the criteria.

According to still further features in the described preferredembodiments, the hybrid heating system further includes a storage tankadapted to provide a heated flow of water for a consumer.

According to still further features in the described preferredembodiments, the first heated flow of liquid and the second heated flowof liquid are disposed in a common line or pipe, whereby the firstheated flow of liquid and the second heated flow of liquid aresubstantially identical.

According to still further features in the described preferredembodiments, the processor is further adapted to control the operationof the heat pump water heating system to increase the thermal storageduring periods of off-peak electricity rates.

According to still further features in the described preferredembodiments, the processor is adapted to receive a manual input of theforecast.

According to still further features in the described preferredembodiments, the processor is adapted to receive occupancy datapertaining to a known occupancy of the consumer network adapted tofluidly communicate with the thermal storage arrangement.

According to still further features in the described preferredembodiments, the processor is adapted to process the occupancy data toat least partially effect the forecast.

According to still further features in the described preferredembodiments, the processor is adapted to receive estimated occupancydata pertaining to an estimated occupancy of the consumer network.

According to still further features in the described preferredembodiments, the processor is adapted to process the estimated occupancydata to at least partially effect the forecast.

According to still further features in the described preferredembodiments, the processor is adapted to automatically receive datapertaining to the forecast.

According to still further features in the described preferredembodiments, the processor is adapted to automatically receive datapertaining to registration data in the consumer network.

According to still further features in the described preferredembodiments, the consumer network includes a hospital.

According to still further features in the described preferredembodiments, the consumer network includes a hotel.

According to still further features in the described preferredembodiments, the consumer network is selected from the group of networksincluding an industrial factory, a building, a neighborhood, an armyfacility, a home, and a prison.

According to still further features in the described preferredembodiments, the forecast is at least partially based on informationpertaining to a current water consumption of the hybrid heating system.

According to still further features in the described preferredembodiments, the forecast is at least partially based on informationpertaining to a historical hot water demand trend.

According to still further features in the described preferredembodiments, the historical hot water demand trend is dependent on atime of day.

According to still further features in the described preferredembodiments, the historical hot water demand trend is of the hybridheating system.

According to still further features in the described preferredembodiments, the historical hot water demand trend is seasonallydependent.

According to still further features in the described preferredembodiments, the historical hot water demand trend is correlated to atleast one weather condition.

According to still further features in the described preferredembodiments, the forecast is based on information pertaining to ahistorical hot water demand for a same day of a week as a current day ofoperating the hybrid system.

According to still further features in the described preferredembodiments, the increase in the thermal storage is an increase in anaverage thermal storage.

According to still further features in the described preferredembodiments, the increase in the average thermal storage includes anincrease of at least 10% of available heat of the average thermalstorage.

According to still further features in the described preferredembodiments, the increase in the average thermal storage includes anincrease of at least 25% of available heat of the average thermalstorage.

According to still further features in the described preferredembodiments, the increase in the thermal storage is at least partiallyeffected by controlling a fill volume of the thermal storage.

According to still further features in the described preferredembodiments, the increase in the thermal storage is at least partiallyeffected by increasing a temperature of the water produced by the heatpump water heating system.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice. Throughout thedrawings, like-referenced characters are used to designate likeelements.

In the drawings:

FIG. 1 is a schematic block diagram of a hybrid heating and conditioningsystem in accordance with the present invention;

FIG. 2 is a schematic flowsheet of a hybrid heating and conditioningsystem according to the present invention;

FIG. 2A provides a portion of a schematic flowsheet of a hybrid heatingand conditioning system according to another preferred embodiment of thepresent invention;

FIG. 2B provides a portion of a schematic flowsheet of a hybrid heatingand conditioning system according to yet another preferred embodiment ofthe present invention, and

FIG. 3 is an exemplary graph of hourly hot water demand and specificfuel and electricity costs as a function of time of day, for a hybridheating system operating in a consumer network, according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principles and operation of the hybrid heating and conditioningsystem of the present invention may be better understood with referenceto the drawings and the accompanying description.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

In a first aspect, the present invention provides a method and systemfor water heating that takes advantage of a time-of-use pricing schemeand/or the high coefficient of performance of heat pump systems. Thesystem of the invention includes one or more conventional heaters suchas electric water heaters and fossil fuel burners, and at least one heatpump water heating system. The hybrid heating system of the presentinvention may be configured whereby the heat pump system and theconventional heater are alternative heating systems, either of which maybe solely or singly operated to handle the heating load. The heat pumpsystem and the conventional heater may be operated in alternate fashion,and may succeed each other in a substantially continuous manner. Aprocessor is configured to operate the one or more conventional heaterswhen water heating using conventional heaters is less expensive thanheating by electricity using the heat pump water heating system. Theprocessor is further configured to operate the one or more heat pumpwater heating systems when the operation of the system is less expensivethan the operation of the conventional heating system, for a given heatload or demand.

FIG. 1 is a schematic block diagram of a hybrid heating and conditioningsystem 100 in accordance with one embodiment of the invention. Heatingsystem 100 may provide hot water and/or steam to at least a part of abuilding (not shown in FIG. 1). Heating system 100 may include at leastone conventional burning or heating system 110, e.g., fossil fuelburning heaters, electric coil heaters, etc. Heating system 100 mayfurther include at least one heat pump water heating system 120, and insome cases, at least one chiller or reversible heat pump system 130adapted to cool at least one room or space. Chiller system 130 may befurther adapted, in an opposite mode, to heat at least one room orspace.

Conventional burning or heating system 110 and heat pump water heatingsystem 120 may fluidly communicate with at least one thermal storagetank 125. Chiller system 130 may fluidly communicate with at least onethermal storage tank 135. One or more consumers 140 may receive a supplyof hot water from thermal storage tank 125. One or more consumers 140may also receive a supply of conditioned (hot or cold) water fromthermal storage tank 135, for providing heating or cooling to at leastone room or space. In some cases, air is heated or cooled by this supplyof conditioned water by means of a heat exchanger (not shown), and theconditioned air is then distributed to heat or cool the at least oneroom or space.

Thus, consumers 140 may be categorized as one or more hot waterconsumers 144 and/or one or more conditioning consumers 146.

Operation of conventional heating system 110, heat pump water heatingsystem 120, and chiller system 130 may be advantageously controlled by aprocessor or controller 150. Processor 150 may be adapted to receive atleast one environmental input 151, one or more system inputs 152, one ormore cost inputs 153 pertaining to the cost of power (e.g., fuel andelectricity), one or more efficiency inputs 154 pertaining to theefficiency of conventional heating system 110, and/or heat pump waterheating system 120, and/or chiller system 130, and at least one demandforecast input 155 including data pertaining to, or correlated with,future demand for hot water or other utilities. Processor 150 mayinclude a memory storing a first set of one or more criteria specifyingwhen water is to be heated by conventional heating system 110 and asecond set of one or more criteria specifying when water is to be heatedby heat pump water heating system 120. In some instances, the sets ofcriteria may dictate the simultaneous operation of conventional heatingsystem 110 and heat pump water heating system 120. As will be elaboratedin greater detail hereinbelow, processor 150 processes information fromat least a portion of inputs 151-155 and may control operation ofconventional heating system 110 and heat pump water heating system 120based on these sets of criteria.

FIG. 2 is a schematic flowsheet of a hybrid heating and conditioningsystem 200 in accordance with one embodiment of the invention. Hybridheating and conditioning system 200 may include conventional heatingsystem 110, heat pump water heating system 120, and chiller orreversible heat pump system 130, thermal storage tanks 125 and 135,processor 150, and a plurality of sensors and/or measuring devices suchas flowmeters F1-F8, temperature instruments or indicators T1-T14, ahumidity-measuring instrument H1, and a power-measuring instrument P1.Hybrid heating system 200 may be adapted to connect to hot waterconsumers 144, such as particular hot water consumers 144 a, 144 b, and144 c. Hybrid heating system 200 may be further adapted to connect toconditioning consumers 146, such as particular conditioning consumers146 a, 146 b, and 146 c.

Thermal storage tank 125, which may be operated as a pressurized vessel(typically at least 2-3 barg), may be heated by conventional heatingsystem 110 and/or heat pump water heating system 120. Hot water may becirculated to hot water consumers 144 a, 144 b, and 144 c via a hotwater delivery line 129 of thermal storage tank 125. Unused hot watermay be returned to storage tank 125 via a recirculation line 128.

Similarly, conditioning fluid inside thermal storage tank 135 may bechilled by chiller or reversible heat pump system 130, or may be heatedby reversible heat pump system 130 and/or by conventional heating system110. The conditioning fluid, which is usually water, may be circulatedto conditioning consumers 146 such as conditioning consumers 146 a, 146b, and 146 c, via a discharge line 231 of thermal storage tank 135. Ifthe conditioning fluid is a gas like air, a thermal storage tank such asthermal storage tank 135 may be unnecessary. After transferring cold orheat to consumers 146 a, 146 b, and/or 146 c, the conditioning fluid maybe returned to thermal storage tank 135 via a return line 233 of thermalstorage tank 135.

Heat pump water heating system 120 may include a compressor 121, a firstheat exchanger or condenser 122, an expansion valve 123, a second heatexchanger or evaporator 124, and a refrigerant (not shown) such as aFreon, disposed within and circulated within heat pump water heatingsystem 120. While Freon has been used as an exemplary refrigerant, oneof ordinary skill in the art will readily appreciate that variousrefrigerants or mixtures of refrigerants may be employed, includingwater, carbon dioxide and ammonia.

The cyclic operation of exemplary heat pump water heating system 120works substantially as follows: compressor 121 compresses therefrigerant gas, raising the pressure and temperature of the gas. Infirst heat exchanger 122, the refrigerant gas is subjected to anindirect (surface) heat exchange arrangement with respect to a flow ofwater (e.g., a flow of water coming at least partially from storage tank125), via a cold or inlet water line or pipe 206. At least a portion ofthe refrigerant gas condenses to form a liquid phase, whereby the latentheat of the refrigerant may be substantially transferred to the flow ofwater coming from storage tank 125.

Subsequently, the liquid refrigerant (or the at least partiallycondensed refrigerant fluid) flows through expansion valve 123, reducingthe pressure and temperature of the liquid refrigerant. The evaporationtakes place in second heat exchanger 124: the cooled refrigerant isheated by a heating fluid (e.g., forced air circulation using ambientair, by means of forced air circulation unit 124 a, or water or liquidfrom a water or liquid reservoir) in second heat exchanger 124, wherethe refrigerant liquid is evaporated. The cycle then repeats: therefrigerant gas is delivered to, and compressed by, compressor 121, asdescribed hereinabove.

While heat pump water heating system 120 has been described as anelectrically powered, compressor driven system, one of ordinary skill inthe art will readily appreciate that various heat pump systems may beemployed. One prominent example is a fuel-powered heat pump system(e.g., operating on natural gas) in which a chemical process maysubstitute for the motor-driven compressor. Another example is a heatpump system utilizing carbon dioxide (or another non-condensing gas) asthe refrigerant, in which case, the refrigerant may not undergo a phasechange (e.g., within either heat exchanger). Another example is a heatpump system utilizing water (or another liquid) as the refrigerant, inwhich case, a vacuum pump or the like may be used to increase thepressure of the water, instead of the compressor described hereinabove.

Chiller or reversible heat pump system 130 may include substantially thesame equipment as heat pump water heating system 120. In chilling mode,however, chiller system 130 operates in a reverse direction with respectto heat pump water heating system 120, such that the conditioning fluidis cooled before being circulated to conditioning consumers 146 via adischarge line 232 of thermal storage tank 135.

When conditioning consumers 146 require heat (e.g., in the winter), thedirection of heat pump system 130 may be reversed, such that theconditioning fluid is heated before being circulated to conditioningconsumers 146 via a discharge line 232 of thermal storage tank 135.

Conventional heating system 110 includes a boiler 112 and may include aheat exchanger 113 adapted to indirectly exchange heat between a hotstream from boiler 112 and inlet water pipe 204 associated with storagetank 125. Conventional heating system 110 may include a second heatexchanger 114 adapted to indirectly exchange heat between a hot streamfrom boiler 112 and cold water pipe 234 fluidly communicating withstorage tank 135.

Flowmeter F3 may advantageously measure a flow quantity (e.g., volume)or flowrate of fuel to boiler 112.

Processor 150 may be adapted to receive information from varioustemperature instruments (e.g., thermocouples), such as T1-T14, andflowmeters (magnetic flowmeters, volumetric gauges, etc.) such as F1-F8.These instruments may provide signals pertaining to system inputs suchas, but not limited to, make-up water temperature (by means of T1) andmake-up water flow quantity or flowrate (by means of F1), watertemperature out of storage tank 125 (by means of T2), water temperatureof recirculated water being returned from consumers 144, viarecirculation line 128, to storage tank 125 (by means of T3), flowquantity or flowrate in circulation line 126 (by means of F2), flowquantity or flowrate of fuel to conventional heating system 110 (bymeans of F3), and power consumption of heat pump system 120 (by means ofP1).

Processor 150 may be further adapted to receive information pertainingto one or more environmental inputs 151, such as, but not limited to,ambient temperature (by means of T4) and humidity or relative humidity(by means of H1).

Processor 150 may be further adapted to receive one or more cost inputs153 pertaining to the cost of fuel and electricity. Typically, the costof fuel is location-specific, and may depend on the amount of fuelpurchased. Consequently, it may be advantageous to have the cost of fuelmanually uploaded, e.g., by an operator of the system. The cost ofelectricity may vary according to the time of day (24 hours), the day ofthe week, and the season. The electricity tariff may advantageously beinput from a database such as a web-based database, e.g., from a websiteof the electricity provider.

Processor 150 may advantageously include a memory storing criteriaspecifying when the first flow of water is to be heated by the heat pumpwater heating system, and when the first flow of water is to be heatedby the conventional heating system. Such criteria may dictate thesimultaneous operation of conventional heating system 110 and heat pumpwater heating system 120.

Processor 150 may be further adapted to receive one or more efficiencyinputs 154 pertaining to the efficiency of conventional heating system110, and/or heat pump water heating system 120, and/or chiller system130. The efficiency may be, or may be based on, a rated efficiency, suchas a manufacturer's rated efficiency.

However, we have found the use of a calculated efficiency to beparticularly advantageous. For the conventional heating system, thecalculated efficiency may be based on the actual efficiency of theconventional heating system over a particular or pre-determined periodof time, for example, a one-time measurement-based calculation of heattransferred to the water per measured fuel consumption. The measurementsand efficiency calculations may span over a number of hours or days, forexample, at least 0.25 hours, at least 1 hour, at least 3 hours, atleast 24 hours, or at least 7 days. The measurements and efficiencycalculations may span over the last X number of hours or days (X>0), forexample, the last hour, the last 3 hours, the last 24 hours, or the last7 days.

Preferably, the power measurement is measured in cumulative fashion overeach period.

By way of example, the measurement-based calculation of heat transferredto the water may be performed by measuring the temperature of the waterintroduced to boiler 112, the temperature of the heated water exiting ofboiler 112, and the flowrate of the water (identical for both streams).

Alternatively or additionally, the calculated efficiency may be based onthe current time place within the maintenance time cycle. We have foundthat after cleaning and major maintenance of conventional heatingsystems such as fossil-fuel burning systems, the actual efficiency maychange appreciably and to a large degree repeatably—over time. Forexample, the measured efficiency of a particular fossil-fuel burningsystem may decrease from about 80% after an annual maintenance andcleaning procedure, to about 65% after 12 months of operation. Given, byway of example, a substantially linear decrease (or other monotonicdecrease) in efficiency, after 8 months of operation, the estimatedefficiency would be:

80%−(8/12)*(80%−65%)=70%.

Regarding the heat pump water heating system, the calculated orestimated coefficient of performance (COP) may be based, at least inpart, on the actual, measurement-based calculation of the COP of theheat pump water heating system over at least one particular orpre-determined period of time. Preferably, the calculated or estimatedCOP may be based, at least in part, on the COP attained during similaroperating conditions including similar ambient temperatures, relative orabsolute humidity, and similar energy demand.

When the at least one particular period of time is a plurality ofparticular periods of time, each of those periods may be at least 1minute, at least 2 minutes, at least 5 minutes, or at least 15 minutes.

In one preferred embodiment, the calculated or estimated COP may be atleast partly based on COP values attained by, or simulated for, thesystem under similar ambient temperatures, e.g., within ±2° C., within±1.5° C., within ±1.2° C., or within ±1.0° C.

In another preferred embodiment, the calculated or estimated COP may beat least partly based on COP values attained by, or simulated for thesystem under similar relative or absolute humidities, e.g., within ±15%,within ±10%, within ±8%, or within ±5%.

In yet another preferred embodiment, the calculated or estimated COP maybe at least partly based on COP values attained by, or simulated for thesystem under similar make-up water flow quantities or flowrates, e.g.,within ±30%, within ±20%, within ±15%, or within ±12%.

In yet another preferred embodiment, the calculated or estimated COP maybe at least partly based on COP values attained by, or simulated for,the system under similar make-up water temperatures, e.g., within ±3°C., within ±2° C., or within ±1.5° C.

In yet another preferred embodiment, the calculated or estimated COP maybe at least partly based on COP values attained by, or simulated for thesystem under similar energy demand or forecasted energy demand, e.g.,within ±30%, within ±20%, within ±15%, or within ±12%.

Alternatively or additionally, processor 150 may perform a regression,or utilize a regression, e.g., based on measured values of the system,measured values of a similar system, and the like. The regression (oranother modeling method) may find a particular relation (e.g., a linearrelation) between the COP and a one or more of the following parameters:ambient temperature, ambient humidity, inlet water flow rate, inletwater temperature, energy demand, etc. Once established, thisrelationship may be expressed as a formula or another mathematical model(e.g., a look-up table), allowing a forecast of the expected COP, givenspecific values of the above-mentioned parameter or parameters. Thisformula may be occasionally re-calculated or updated as further data onsystem performance is obtained.

The measurement-based calculation of the COP may be effected bymeasuring the temperature of the water flowing towards, or introduced tocondenser 122, e.g., via cold or inlet water pipe 206, the temperatureof the heated water exiting or heading away from condenser 122, e.g.,via hot or outlet pipe 208, and the flowrate of the water (identical forboth streams). Similarly, if there is a secondary (or tertiary, etc.)circulation arrangement in the system, as shown by way of example inFIGS. 2A and 2B, the temperature indicators may be disposed thereon(e.g., before and after the secondary heat exchanger), and themeasurement of heat transfer may be based on a difference between themeasured temperatures, and on a measured, estimated, or calculatedflowrate and heat capacity of the liquid flowing within the circulationarrangement.

Demand forecast input 155 may include demand forecast data based onknown or estimated occupancy data. Such data may be automaticallyavailable to processor 150, e.g., via a communication line associatedwith a computer containing registration data for the consumer network,building or organization (e.g., a hotel or hospital) having hot waterconsumers 144 and/or conditioning consumers 146. Alternatively oradditionally, such data may be manually input to processor 150. Forexample, the hotel staff may be alerted that 2 busses containingtourists are to unexpectedly arrive at the hotel within an hour. Thehotel staff may then input demand forecast input 155 pertaining toapproximately 100 new arrivals to the hotel.

Processor 150 may include a memory storing a first set of one or morecriteria specifying when water is to be heated by conventional heatingsystem 110 and a second set of one or more criteria specifying whenwater is to be heated by heat pump water heating system 120. As will beelaborated in greater detail hereinbelow, processor 150 processesinformation from at least a portion of inputs 151-155 and may controloperation of conventional heating system 110 and heat pump water heatingsystem 120 based on these sets of criteria.

Processor 150 may advantageously include, or be associated with, aclock. Processor 150 may also include a user input device, such as akeypad, which allows a user to manually input any of inputs 151-155.

We will now proceed to describe, in exemplary fashion, operation ofhybrid heating and conditioning system 200 in accordance with anotheraspect of the present invention.

Conditioning for Consumers

In cooling mode, chiller system 130 operates as a heat pump to transferheat from the fluid (typically water) in a return line 244 to theenvironment. The chilled fluid is recirculated to storage tank 135, andfrom there to at least one conditioning consumer 146. For example, thechilled fluid may be used to cool particular conditioning consumers 146a, 146 b, and 146 c by means of a heat exchanger associated with theseconditioning consumers. One skilled in the art will readily appreciatethat the chilled fluid may be used to indirectly cool particularconditioning consumers 146 a, 146 b, and 146 c, e.g., by cooling astream of air that is then circulated to consumers 146 a, 146 b, and 146c.

Hot Water Supply for Consumers

Hybrid heating system 200 is adapted to supply hot water for consumptionby at least one consumer 144 in at least two modes: conventional heatingmode using conventional heating system 110, and heat pump heating modeusing heat pump water heating system 120.

In the conventional heating mode, water to be heated may be deliveredfrom storage tank 125 to (surface) heat exchanger 113 via inlet waterpipe 204. A hot fluid such as water is circulated from boiler 112 toheat exchanger 113, where heat is delivered from the hot fluid to thewater, which may be returned to storage tank 125 or introduced toanother storage facility. Flowmeter F3 may be utilized to measure a flowquantity (e.g., volume) or flowrate of fuel to boiler 112, in order tocalculate fuel consumption.

In the heat pump heating mode, water to be heated may be circulated fromstorage tank 125 to (surface) condenser 122 via cold or inlet water pipe206. Heat provided to the water is mainly from the latent heatassociated with the condensation of the refrigerant gas. The heatedwater may be returned to storage tank 125 (e.g., via hot or outlet pipe208) or introduced to another storage facility. The heated water mayalso be passed through heat exchanger 113, as will be elaboratedhereinbelow. Power-measuring instrument P1 may be utilized to measurethe power consumption of heat pump water heating system 120, or thepower consumption of compressor 121, which is the main power consumer ofsystem 120.

In both the conventional heating mode and the heat pump heating mode,the heated water is delivered from, and returned to, one or more storagetanks such as storage tank 125, via circulation line 126. Hot waterdelivery line 129, which is a section of circulation line 126, isutilized to deliver the heated water to at least one consumer 144, suchas particular hot water consumers 144 a, 144 b, and 144 c. Unconsumedhot water is returned to storage tank 125, via another section ofcirculation line 126, recirculation line 128.

Temperature indicator T2 may be disposed on hot water delivery line 129.Temperature indicator T3 may be disposed on recirculation line 128.Flowmeter F2 may be disposed anywhere on circulation line 126.

Make-up water may be introduced, via pipe 202, to storage tank 125, orvia make-up lines 202 a and 202 b, to cold water pipes 204 or 206associated with storage tank 125. At least one flowmeter F1 may bedisposed on lines 202, 202 a and/or 202 b to provide a total flow orflowrate of the make-up water.

One of ordinary skill in the art will readily envision the use of valves(such as solenoid valves or electrically-controlled valves) and thelike, as well as any other auxiliary equipment, to control hybridheating system 200 in general, and heat pump system 130, heat pump waterheating system 120, and conventional heating system 110, in particular.

FIG. 2A provides a portion of a schematic flowsheet of a hybrid heatingand conditioning system according to another preferred embodiment of thepresent invention. The flowsheet may be largely identical to theflowsheet provided in FIG. 2, with the exception of the interfacebetween storage tank 125 and condenser 122. The system includes anadditional or secondary surface heat exchanger 422 that may be disposed,from a process standpoint, between condenser 122 and the consumer, or asshown, storage tank 125. Between condenser 122 and heat exchanger 422 isa primary loop, cycle, or circulation arrangement 430, in which a heatexchange fluid, typically a liquid, is introduced to condenser 122 via aline or condenser inlet 401 b. After absorbing heat within condenser 122(the primary heat exchanger), the heated heat exchange fluid may exitcondenser 122 via line or condenser outlet 401 a.

The heated heat exchange fluid may then transfer heat to another,secondary fluid (typically a liquid such as water), in heat exchanger422. Between storage tank 125 and heat exchanger 422 is a secondaryloop, cycle, or circulation arrangement 440, which may be adapted tointroduce the secondary fluid to heat exchanger 422 via a line or pipe402 b. After absorbing heat within heat exchanger 422 (the secondaryheat exchanger), the heated secondary fluid may exit heat exchanger 422via line or pipe 402 a. Temperature indicators and/or flow indicatorsmay be installed on lines 401 a, 401 b, 402 a, and/or 402 b, as well ason lines 204 a and 204 b, and the information may be provided to theprocessor for calculation and control purposes.

FIG. 2B provides a portion of a schematic flowsheet of a hybrid heatingand conditioning system according to another preferred embodiment of thepresent invention. While largely similar to the flowsheet provided inFIG. 2A, the secondary fluid within the secondary loop may pass throughheat exchanger 113 (via lines 204 a and 204 b) prior to being returnedto storage tank 125. Alternatively or additionally, the secondary fluidwithin the secondary loop may not be returned to storage tank 125,rather the secondary fluid may be provided directly to a consumer via aline connected to line 402 a (in FIG. 2A) or via a line connected lineto 204 a or 204 b (in FIG. 2B).

FIG. 3 is an exemplary graph of hourly hot water demand and specificfuel and electricity costs as a function of time of day, for aninventive system such as hybrid heating system 200, operating in aconsumer network such as a hotel. The hourly hot water demand or load,plotted on the 1^(st) Y-axis, attains a maximum at around 7 AM,presumably when a large portion of particular consumers are showering.The hourly electricity consumption is near-minimum between midnight and5 AM, presumably when many of the consumers are sleeping, and againbetween 10 AM and 2 PM, presumably when many of the consumers are not onthe premises.

The specific electricity cost is plotted on the 2^(nd) Y-axis, as afunction of time of day. Three rates are observed: a peak rate of 17.8¢/kWh; a mid-peak rate of 11.4 ¢/kWh, and an off-peak rate of 4.2 ¢/kWh.In this example, the off-peak rate is less than 25% of the peak rate.

The specific fuel cost is also plotted on the 2^(nd) Y-axis, as afunction of time of day. Per unit power, the fossil fuel used to fireheating system 110 is observed to be less expensive during most hours ofthe day. However, processor 150 may calculate or estimate (or beprovided with) both:

-   -   the coefficient of performance (COP) of heat pump water heating        system 120, and    -   the thermal efficiency of heating system 110.        Thus, processor 150 may calculate and compare the cost of        operating heat pump water heating system 120 and heating system        110, and control operation of the two systems to reduce or        minimize cost.

Features of Processor 150

In addition to the features of processor 150 described hereinabove,processor 150 may also have the following features:

-   -   1. processor 150 may be adapted to receive and to process cost        data pertaining to conventional heating system 110 and heat pump        water heating system 120, along with data pertaining to at least        one ambient parameter or condition and/or various system        parameters, and to control operation of heating system 110 and        heat pump water heating system 120 based, at least partially, on        these inputs.    -   2. processor 150 may be adapted to control operation of heat        pump water heating system 120 concurrently with operation of        heat pump system 130, wherein system 120 and system 130 operate        in opposite heating modes. Thus, heat pump water heating system        120 can heat water while system 130 is in cooling mode.        -   Moreover, even when system 130 is in cooling mode, processor            150 utilizes the cost data in deciding (by means of a            decision algorithm, sets of criteria, etc.) whether to            operate heating system 110 or heat pump water heating system            120.    -   3. processor 150 may be adapted to control operation of heat        pump water heating system 120 to increase a thermal storage of        the thermal storage arrangement during periods of off-peak        electricity rates (i.e., based on a “time-of-use” pricing        scheme). To this end, it may be advantageous to have a thermal        storage arrangement, associated with heat pump water heating        system 120, having a holdup volume of at least 500 liters        (preferably, at least 1,000 or at least 2,000 liters, and in        some cases, at least 6,000 liters, at least 10,000 liters, or at        least 15,000 liters) per 100 kW capacity of system 120.    -   4. The increase in thermal storage may be effected by increasing        the fill volume of the thermal storage. Alternatively or        additionally, the increase in thermal storage may be effected by        increasing the temperature of the water produced by heat pump        water heating system 120.    -   5. processor 150 may be adapted to control operation of heat        pump water heating system 120 to increase a thermal storage of        the thermal storage arrangement responsive to a forecast        pertaining to a hot water load or demand.        -   The forecast may be based on known or estimated occupancy            data. Such data may be automatically available to processor            150, e.g., via a communication line associated with a            computer containing registration data for the central body,            building or organization (e.g., a hotel or hospital) having            hot water consumers 144 and/or conditioning consumers 146.            Alternatively or additionally, such data may be manually            input to processor 150. For example, the hotel staff may be            alerted that 2 busses containing tourists are to            unexpectedly arrive at the hotel within an hour. The hotel            staff may then input demand forecast input 155 pertaining to            approximately 100 new arrivals to the hotel.        -   Processor 150 may be further adapted to receive at least one            demand forecast input 155 including data pertaining to, or            correlated with, future demand for hot water or other            utilities.        -   Demand forecast input 155 may be at least partially based on            a current value or estimation of hot water demand or            consumption, e.g., by receiving an input from flowmeter F1            pertaining to a current flowrate of the make-up water (e.g.,            within the last ½ hour, within the last hour, within the            last 2 hours), that may provide some indication of the            expected demand. Demand forecast input 155 may include            demand forecast data based on typical or historical demand            trends as a function of time of day. Such demand forecast            data may include seasonal demand trends, demand from the            same day of the week (from the previous week, previous            month, etc.), demand from at least one period having similar            weather conditions, etc.    -   6. processor 150 may be adapted to control operation of heating        system 110 and heat pump water heating system 120 based on a        first predicted efficiency or performance of heat pump water        heating system 120 that is dependent on the at least one ambient        parameter (or another parameter extensive to the system, such as        flowrate and/or temperature of the make-up water), and a second        predicted efficiency or performance pertaining to the        conventional heating system 110. Typically, the at least one        ambient parameter includes an ambient temperature and an ambient        humidity.        -   The predicted efficiency or performance of conventional            heating system 110 may be dependent on a forecast of a hot            water load or demand.        -   The predicted efficiency may be dependent on a variable            efficiency parameter of conventional heating system 110. For            example, the variable efficiency parameter may provide an            estimated efficiency of heating system 110 based on a time            position within a maintenance cycle of heating system 110.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions, illustrate the invention in a non-limiting fashion.

Example 1

The annual fuel cost of a hotel operating a conventional heating system(“System I”) is calculated by a simulator to be 106,800 Euros. A heatpump water heating system is then integrated with the conventionalheating system, along with a processor adapted to receive and to processcost data and efficiency and COP data pertaining to the conventionalheating system and the heat pump water heating system, and to controloperation of the heating system and the heat pump water heating systembased on these inputs.

A COP of 2.8, corresponding to the nominal (manufacturer's) COP rating,is provided to the processor.

Utilizing this integrated system (“System II”), the simulator calculatesan annual fuel cost of 94,925 Euros, a cost reduction of about 11.1%.

The simulation is then performed using a COP of 2.35, corresponding toan average measured COP value of the system, under actual operatingconditions (“System III”). Utilizing this average measured COP value,the simulator calculates an annual fuel cost of 84,694 Euros, a costreduction of about 20.7% with respect to the original heating system,and an additional cost reduction of about 10.8% with respect to SystemII.

Moreover, with respect to System III, System II makes a wrong decisionregarding which heating system to operate (or which system iseconomically preferable) in approximately 37% of the decisions.

Example 2

The annual fuel cost of a hotel operating a conventional heating system(“System I”) is calculated by a simulator to be 120,150 Euros. A heatpump water heating system and processor are then integrated with theconventional heating system, as in System III of Example 1.

The simulation is then performed using a COP of 2.35, corresponding toan average measured COP value of the system, under actual operatingconditions. Utilizing this average measured COP value, the simulatorcalculates an annual fuel cost of 93,112 Euros, a cost reduction ofabout 22.5% with respect to the original heating system.

The processor is then further adapted to control the operation of theconventional heating system and the heat pump water heating system basedon a predicted (correlated) performance of the heat pump water heatingsystem that is dependent on the ambient temperature (“System IV”).Regression is performed on actual system data (under actual operatingconditions) to obtain the correlation, i.e., the heat pump water heatingsystem performance (COP) as a function of the ambient temperature.

Utilizing this correlated COP value, the simulator calculates an annualfuel cost of 86,101 Euros, a cost reduction of about 28.3% with respectto the original heating system, and an additional cost reduction ofabout 9.2% with respect to System III.

Moreover, with respect to System IV, System III makes a wrong decisionregarding which heating system to operate (or which system iseconomically preferable) in about 26% of the decisions.

As used herein in the specification and in the claims section thatfollows, the term “conventional heating system” is specifically meant toinclude fossil-fuel consuming systems such as various liquid-fuel (e.g.,oil, diesel fuel, gasoline, natural gas) burning systems, and solid-fuel(e.g., coal) burning systems; biomass consuming systems, includingcellulose, lignin, and any products and/or by-products thereof; andelectrical heating systems such as resistance (e.g., coil) heaters. Theterm “conventional heating system” is specifically meant to exclude heatpump systems such as a heat pump water heating system, whether poweredby electricity, liquid fuel, or other means.

As used herein in the specification and in the claims section thatfollows, the term “opposite heating modes”, with respect to two heatpump systems, refers to a state in which one of the heat pump systemsoperates in a heating mode, so as to heat water or other heat-exchangefluid while cooling the environment, while the other heat pump systemoperates in a cooling mode, so as to cool water or other heat-exchangefluid while pumping heat to the environment.

As used herein in the specification and in the claims section thatfollows, the term “fossil fuel” refers to fuels derived from livingmatter, typically from a previous geological time or period, such fuelsincluding diesel fuel, coal, liquid petroleum gas (LPG), natural gas,and heavy (or crude) oil.

As used herein in the specification and in the claims section thatfollows, the term “to direct a heated flow of liquid towards theconsumer” and the like, refers to a flow of heated liquid, typicallywater, that is directly delivered to the consumer (e.g., sink, showerstall, radiator, swimming pool), indirectly delivered to the consumer(e.g., via a storage tank) or is delivered to another heat exchanger(e.g., in a secondary loop or cycle), to produce another heated flow ofliquid that is directed towards the consumer. As a first example, in aheat pump system having solely a primary loop or arrangement, the heatedflow of liquid may be pumped directly to the consumer such as consumer144 a or 146 a of FIG. 2, or the heated flow of liquid may be pumped tothe heat exchanger (e.g., exchanger 113) to absorb additional heatbefore being pumped to the storage tank or directly to the consumers. Asa second example, in a heat pump system having a primary circulationarrangement and a secondary circulation arrangement (e.g., primary loop430 and secondary loop 440 of FIG. 2A), the heated flow of liquid may bepumped to the secondary heat exchanger (e.g., exchanger 422) whereby thewater ultimately delivered to the consumers (e.g., via line 129) isfirst heated in the secondary heat exchanger.

It will be appreciated that certain features of the invention, whichare, for clarity, described in the context of separate embodiments, mayalso be provided in combination in a single embodiment. Conversely,various features of the invention, which are, for brevity, described inthe context of a single embodiment, may also be provided separately orin any suitable sub-combination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

What is claimed is:
 1. A hybrid heating system comprising: (a) a heatpump water heating system including: (i) a pressurizing arrangement,associated with a refrigerant circulation pipe, adapted to increase apressure of a first refrigerant fluid to produce a pressurizedrefrigerant fluid; (ii) a first heat exchange system including: aprimary circulation arrangement, including, and fluidly communicatingwith, a first heat exchanger, said first exchanger fluidly communicatingwith said refrigerant circulation pipe, said first exchanger and saidprimary circulation arrangement adapted to effect an indirect heatexchange between a first flow of liquid and said pressurized refrigerantfluid, whereby heat is transferred from said pressurized refrigerantfluid to said first flow of liquid to produce a first heated flow ofliquid, and whereby an enthalpy-reduced refrigerant fluid is produced,said heat exchange system optionally including at least a secondarycirculation arrangement having, and fluidly communicating with, asecondary heat exchanger, (iii) a depressurizing arrangement, fluidlycommunicating with said refrigerant circulation pipe, and adapted toreceive said enthalpy-reduced refrigerant fluid and to reduce a pressurethereof, to produce a depressurized refrigerant fluid having a lowerpressure than said enthalpy-reduced fluid, and (iv) a second heatexchanger, said second exchanger fluidly communicating with saidcirculation pipe, and adapted to effect an exchange of heat between saiddepressurized refrigerant fluid and a heat source, whereby said firstrefrigerant fluid is produced; (b) a plurality of sensors, each adaptedto measure at least one system parameter, said plurality of sensorsincluding at least a first temperature sensor and a second temperaturesensor associated with said heat exchange system; (c) an inputarrangement adapted to provide cost data pertaining to a first powercost for supplying power to said heat pump water heating system, and tocost information pertaining to a second power cost for operating aconventional heating system; (d) a processor including a memory storingcriteria specifying when to operate said heat pump water heating system,and when to operate said conventional heating system, said processoradapted to receive and to process: (i) said cost data; (ii) said costinformation; (iii) data pertaining to said at least one systemparameter; (iv) flow information pertaining to a flowrate of a liquidwithin any said circulation arrangement of said first heat exchangesystem, and (v) power consumption information pertaining to a powerconsumption of at least a portion of said heat pump water heatingsystem; said processor further adapted to concurrently operate, upondemand, said heat pump water heating system along with a chiller systemin opposite heating modes; wherein, when said chiller system operates ina cooling mode, said processor is adapted to receive and to process saidcost data, said cost information, said data pertaining to said at leastone system parameter, said flow information pertaining to a flowrate ofsaid first flow of liquid, and said power consumption informationpertaining to a power consumption of at least a portion of said heatpump water heating system, and to control operation of said conventionalheating system and said heat pump water heating system based on saidcriteria.
 2. The hybrid heating system of claim 1, said processoradapted to calculate and compare a cost of operating said heat pumpwater heating system and a cost of operating said conventional heatingsystem, based on said cost data, said cost information, said datapertaining to said at least one system parameter, said flow information,and said power consumption information.
 3. The hybrid heating system ofclaim 1, wherein said processor is adapted to utilize said cost data andto decide whether to operate said conventional heating system or tooperate said heat pump water heating system.
 4. The hybrid heatingsystem of claim 1, further including a power consumption sensor adaptedto provide said power consumption information, and further including aflow sensor, associated with any said circulation arrangement, andadapted to provide said flow information.
 5. The hybrid heating systemof claim 1, wherein, based on said criteria, said processor is adaptedto operate said conventional heating system and said heat pump waterheating system in a simultaneous mode.
 6. The hybrid heating system ofclaim 1, said processor further adapted to control operation of saidconventional heating system and said heat pump water heating systembased on a first predicted performance of said heat pump water heatingsystem, said predicted performance dependent on at least one parameterselected from the group of parameters consisting of an ambientparameter, an inlet liquid temperature to said first exchanger, and aninlet liquid flowrate to said first exchanger.
 7. The hybrid heatingsystem of claim 6, said processor further adapted to control operationof said conventional heating system and said heat pump water heatingsystem based on a second predicted performance of said conventionalheating system.
 8. The hybrid heating system of claim 7, said secondpredicted performance being dependent on a forecast of a hot water loador demand.
 9. The hybrid heating system of claim 8, said at least oneambient parameter including an ambient humidity.
 10. The hybrid heatingsystem of claim 1, said criteria being at least partly based oncoefficient of performance (COP) information pertaining to said heatpump water heating system.
 11. The hybrid heating system of claim 10,said COP information being derived from said data pertaining to saiddata pertaining to said at least one system parameter, said flowinformation, and said power consumption information.
 12. The hybridheating system of claim 10, said COP information including an averageCOP of said heat pump water heating system, said average based on aplurality of said one particular period of time.
 13. The hybrid heatingsystem of claim 10, said COP information being based on a plurality ofactual COP data previously attained by said heat pump system.
 14. Thehybrid heating system of claim 13, said plurality of actual COP databeing weighted according to a similarity criterion between pastoperating conditions and present operating conditions of said heat pumpwater heating system.
 15. The hybrid heating system of claim 10, saidCOP information being based on a regression of a plurality of actual COPdata previously attained by said heat pump system, wherein a weightingof said actual COP data is based on a similarity criterion between pastoperating conditions and present operating conditions of said heat pumpwater heating system.
 16. A hybrid heating system comprising: (a) a heatpump water heating system including: (i) a pressurizing arrangement,associated with a refrigerant circulation pipe, adapted to increase apressure of a first refrigerant fluid to produce a pressurizedrefrigerant fluid; (ii) a first heat exchange system including: aprimary circulation arrangement, including, and fluidly communicatingwith, a first heat exchanger, said first exchanger fluidly communicatingwith said refrigerant circulation pipe, said first exchanger and saidprimary circulation arrangement adapted to effect an indirect heatexchange between a first flow of liquid and said pressurized refrigerantfluid, whereby heat is transferred from said pressurized refrigerantfluid to said first flow of liquid to produce a first heated flow ofliquid, and whereby an enthalpy-reduced refrigerant fluid is produced,said heat exchange system optionally including at least a secondarycirculation arrangement having, and fluidly communicating with, asecondary heat exchanger, (iii) a depressurizing arrangement, fluidlycommunicating with said refrigerant circulation pipe, and adapted toreceive said enthalpy-reduced refrigerant fluid and to reduce a pressurethereof, to produce a depressurized refrigerant fluid having a lowerpressure than said enthalpy-reduced fluid, and (iv) a second heatexchanger, said second exchanger fluidly communicating with saidcirculation pipe, and adapted to effect an exchange of heat between saiddepressurized refrigerant fluid and a heat source, whereby said firstrefrigerant fluid is produced; (b) a plurality of sensors, each adaptedto measure at least one system parameter, said plurality of sensorsincluding at least a first temperature sensor and a second temperaturesensor associated with said heat exchange system; (c) an inputarrangement adapted to provide cost data pertaining to a first powercost for supplying power to said heat pump water heting system, and tocost information pertaining to a second power cost for operating aconventional heating system; (d) a processor including a memory storingcriteria specifying when to operate said heat pump water heating system,and when to operate said conventional heating system, said processoradapted to receive and to process: (i) said cost data; (ii) said costinformation; (iii) data pertaining to said at least one systemparameter; (iv) flow information pertaining to a flowrate of a liquidwithin any said circulation arrangement of said first heat exchangesystem, and (v) power consumption information pertaining to a powerconsumption of at least a portion of said heat pump water heatingsystem; said processor further adapted to concurrently operate, upondemand, said heat pump water heating system in a heating mode, alongwith a chiller system in a heating mode; wherein, when said chillersystem operates in said heating mode, said processor is adapted toreceive and to process said cost data, said cost information, said datapertaining to said system parameters, said flow information pertainingto a flowrate of said first flow of liquid, and said power consumptioninformation pertaining to a power consumption of at least a portion ofsaid heat pump water heating system, and to control operation of saidconventional heating system and said heat pump water heating systembased on said criteria.
 17. The hybrid heating system of claim 16, saidprocessor adapted to calculate and compare a cost of operating said heatpump water heating system and a cost of operating said conventionalheating system, based on said cost data, said cost information, saiddata pertaining to said at least one system parameter, said flowinformation, and said power consumption information.
 18. The hybridheating system of claim 17, said processor being adapted to utilize saidcost data and to decide whether to operate said conventional heatingsystem or to operate said heat pump water heating system.
 19. The hybridheating system of claim 16, said criteria being at least partly based oncoefficient of performance (COP) information pertaining to said heatpump water heating system.
 20. The hybrid heating system of claim 19,said COP information being based on a regression of a plurality ofactual COP data previously attained by said heat pump system, wherein aweighting of said actual COP data is based on a similarity criterionbetween past operating conditions and present operating conditions ofsaid heat pump water heating system.